1. Field of the Invention
The present invention relates generally to the transfer of data. More specifically, but without limitation thereto, the present invention relates to a centralized bus interface for connecting a payload unit and a spacecraft bus using a single wire secondary distribution.
2. Discussion of the Background Art
Currently the interface between a spacecraft bus and a plurality of payload units requires a separate power line, communication lines and telemetry lines for every payload unit on the spacecraft. The spacecraft bus is the main bus on the spacecraft that is connected to the spacecraft command processor. The spacecraft command processor is the main processor on a spacecraft that sends and receives data from the ground and also sends and receives data from the plurality of payload units on the spacecraft. The plurality of payload units are the electronic sub-systems such as receivers, power amplifiers, frequency converters and low noise amplifiers.
Prior designs include 8 or more wires connecting one payload unit to the spacecraft bus. Each payload unit on the spacecraft has a separate 8 wire connection to the spacecraft bus including 2 wires for power, 4 wires for commands, 2 wires for telemetry and return wires via the chassis. As the size of payload electronics shrinks, the size of the circuitry interfacing with the spacecraft bus must also shrink in order to properly operate. One current approach to reducing the size and weight of the interface circuitry to each payload unit is utilizing smaller components and higher density packaging technologies. Although this has resulted in very good incremental improvements, a new architecture for these interfaces is needed to make a step decrease in the size and weight of the payload units as each payload unit still requires at least an 8 wire interface.
Thus there is a need for an interface design between a spacecraft bus and the payload units which can solve the problems discussed above.